1. Grinding Wheel Installation
Special attention should be paid to installing grinding wheels on the grinder. Because the grinding wheel is working in high speed rotating conditions, the use should be carefully inspected before cracks are permitted. Installation must be reliable and should undergo a static balance adjustment to avoid personal and quality accidents.
The grinding wheel inner hole and the wheel shaft or flange outside the circle, can not be too tight, otherwise grinding when heated expansion, easy to crack the grinding wheel, also can not be too loose, otherwise the grinding wheel prone to eccentric, lose balance, resulting in vibration. The general clearance is 0.1~0.8mm, and the clearance of high-speed wheel is smaller. With flange disc clamping wheel, two flange diameter should be equal, the diameter should not be less than the diameter of the grinding wheel 1/3. In the flange and the grinding wheel end of the application of thick cardboard or oil-resistant rubber gasket, so that the pressure evenly distributed, the NUT tightening force can not be too large, otherwise the grinding wheel will burst. Pay attention to the rotation of fastening threads, should be contrary to the rotation of the grinding wheel, that is, when the wheel rotates counterclockwise, with the right screw thread, so that the grinding wheel in the effect of the force, will drive the nut spin tighter.
2. Grinding Wheel Balance
In general, grinding wheels with greater diameter than 125mm are balanced so that the center of gravity coincides with its rotating axis.
Uneven grinding wheels in high speed rotation will produce vibration, color processing quality and machine tool accuracy, serious when the machine damage and grinding wheel fragmentation. The main cause of imbalance is uneven density of the grinding wheels, asymmetric geometry and eccentric mounting. Therefore, before installing the grinding wheel, balancing the grinding wheel has two kinds of static equilibrium and dynamic equilibrium. In one case, a static equilibrium is needed, but the dynamic equilibrium must be carried out when the high-speed mushroom is cut (faster than 50m/s) and high-degree grinding. The following illustration is a static balancing device for grinding wheels. Balance the grinding wheel on the balance shaft, and then put the kind-hearted shaft of the grinding wheel to the balance rack, the wheel will swing back and forth until the swing stops. A balanced grinding wheel can be stationary at any position.
If the wheel is unbalanced, the heavier part will always go to the following. The position of the balancing block can be moved to balance it. The balanced grinding wheel is mounted to the machine tool spindle before the crack inspection, the cracked grinding wheel is absolutely forbidden. The grinding wheel and flange should be mounted between 0. Elastic pad of 5-1 volumes: the diameter of the two flanges must be equal, and their size is generally half the diameter of the grinding wheel. There should be a certain clearance between the grinding wheel and the wheel shaft or the stair flange, lest the spindle will swell and crack the grinding wheel.
The method of balancing the grinding wheels: in the annular groove of the grinding wheel flange, a few balance blocks are mounted, and the center of the grinding wheel is coincident with its rotating axis by adjusting the position of the balance block.
3. Dressing of grinding wheels
In the grinding process of grinding wheel particles in friction and extrusion, its edges and corners gradually grinding round to blunt, or in grinding ductile materials, grinding debris is often inserted into the surface of the grinding wheel pores, so that the surface of the grinding wheel blocked, and finally the grinding wheel loss cutting ability. At this point, the grinding wheel and the workpiece will be skidding, and can cause vibration and noise, so that the grinding efficiency drops, surface roughness of the difference. At the same time, due to the increase of grinding force and grinding heat, the workpiece deformation and the influence of grinding precision can be caused, and the surface burns and tiny cracks will occur in severe grinding. In addition, because of the uneven hardness of the grinding wheel and the different working conditions, so that the grinding wheel work surface wear uneven, various parts of the grinding particles shedding amount of unequal, resulting in the loss of the wheel profile accuracy, affecting the workpiece surface shape and roughness. In the case of the above, the grinding wheel must be trimmed, cut off the surface of a layer of abrasive, so that the grinding wheel surface to reveal the whole sharp abrasive grains, to restore grinding wheel cutting ability and shape accuracy.